The antibiotic LY146032 is the N-decanoyl derivative of the A-21978C antibiotics and has now been identified as a member of factor A-21978C.sub.0. The A-21978C antibiotics are prepared by fermentation methods described in U.S. Pat. No. 4,208,403. LY146032 methods for its preparation are specifically disclosed in U.S. Pat. No. 4,537,717. In this method A-21978C is prepared by fermentation techniques. The fatty acid side chain then is removed with an enzyme to give the A-21978C nucleus and the nucleus is reacylated with the desired acyl group, for example the n-decanoyl group, to give the A-21978C cyclic peptides as described in U.S. Pat. No. 4,527,717.
An improved method for preparing these cyclic peptides is described by Floyd M. Huber, Richard L. Pieper and Anthony J. Tietz in copending U.S. patent application Ser. No. 773,762, filed Sept. 9, 1985, entitled IMPROVED PROCESS FOR A-21978C DERIVATIVES.
Because of the interest in LY146032 and other therapeutically useful fermentation products and their importance, new and more effective methods of isolating these useful compounds from fermentation mixtures continually are sought.
The novel process of this invention was previously disclosed, but not claimed, in U.S. patent application No. 07/060,148, filed June 10, 1987, for use in purifying the .beta.-isomer of LY146032.